Automatic creation of music by a computer is a brand new field that has only recently come of age. The popular "Band in the Box" by PG Music is an example of computer based music generation directed to the generation of a musical accompaniment (without melody) from the knowledge of a song's chord structure. U.S. Pat. No. 4,399,731 discloses a method and system for generating simple melodies and rhythms for music education. The computer selects notes and rhythms randomly but constrained by specific musical rules to provide some degree of music. This technique is called algorithmic composition and is effective in creating very "novel" music due to a high degree of randomness.
U.S. Pat. No. 4,483,230 discloses a method for generating simple musical melodies for use as an alarm in a watch. The melody is initially defined by a user's control of musical pitch by varying the amount of light reaching the watch. The melody is saved in the watch's memory for subsequent playback as an alarm. The patent requires human intervention for defining a melody.
U.S. Pat. No. 4,708,046 discloses a method for generating simple musical accompaniments for use in an electronic musical keyboard. The accompaniment is derived from pre-stored forms with a degree of randomness that is triggered by the performer's selection of bass notes. The lowest pitch determines the key of the accompaniment and the selection of notes determines the chordal structure. The randomness allows the arrangement to have some variation in playback. Thus, this patent only provides an accompaniment to a person's performance on a musical keyboard.